Thermoresponsive [(PLA)-b-(Car)] based frustum-shaped capsules with extended porosity for biosensing and biomedical applications

We present, a facile method for the synthesis of block co-polymer of [(PLA)-b-(Car)], (PLA-Poly Lactic acid and Car-Carbazole) followed by the development of cone and ice-cream cup-shaped frustums with nanoporous capsules for bio-sensing and drug loading applications. Thermoplastic polyester PLA aminated with an aromatic heterocyclic organic compound Car gives the desired shape and characteristics of the capsules with extended porosity on the surface. The size, shape, and morphology of the capsules are tunable concerning solvents and thermal treatment. Interestingly, the synthesis and development of nanoporous hollow (half-broken coconut type) capsules has been carried out without using any precursors and surfactants. Synthesis of [(PLA)-b-(Car)] has been confirmed through the Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR; 1H and 13C). However, the morphology and surface properties of capsules were confirmed through field emission scanning electron microscopy (FE-SEM), Bruner Emmett Teller (BET), and atomic force microscopy (AFM) characterizations. The capsule size ranges from ~200 nm to 1 µm (in diameter) and porosity scales from ~60 to 80 nm. The hollow and porous surface of the capsules with biosensing and biomedical applications can be considered as a unique and novel characteristic property of our invention. This kind of novel cone and ice cream cup-shaped hollow frustums can be used as a stimuli-responsive catalytic activity through the fluorescence measurement of cysteine and gold nanoparticle [(Cys)-(Au+)] for enhanced payload and biomedical applications.